questions on a 327 harmonic balancer

alrite im supposed to be buying this pontiac grand prix 1981 with a 1969 327 from a vette, i know the guy good and the only problem was the harmonic balancer fell off while he was driving, not even beating on the car just driving, and ive never done anything with harmonic balancers cause im an autobody guy so all i know is that he says its press fit and then this other guy tells me its not press fit u need a bolt to put it on, i looked up some stuff and i was just wondering if anyone knows exactly what harmonic balancer i will need and how to put it on... thank u for ur help.

the harmonic balancer IS a press fit. you need a harmonic balancer/damper puller to get it off and an installer to install it. usually you can buy the tools as a set at almost any parts store or speed shop for under $50. most likely any of your friends who build engines, at least one of them might have one you can borrow